Magnetoactive janus particle swarm metamaterials for information display, memory, and encryption

Abstract

A magnetoactive material is provided. Devices comprising a magnetoactive component with the magnetoactive material are also provided. The magnetoactive component comprises a plurality of multiphasic magnetoactive particles configured to selectively exhibit a swarming pattern when a magnetic force field is applied. Each particle comprises a first phase comprising a first colorant and at least one additional phase distinct from the first phase so that each particle has optically distinct phases. At least one of the first phase or the at least one additional phase comprises a material capable of magnetization and receptive to the magnetic force field. The device may further comprise a magnetic component for selectively generating the magnetic force field directed towards the magnetoactive component. The swarming pattern may be initially encoded and fully reversible, to enable programmable dynamic display, non-volatile and semi-volatile memory, Boolean logic, and information encryption functions in soft, wearable devices among others.

Description

Attorney Docket No. 2115-008421-WO-POAMAGNETOACTIVE JANUS PARTICLE SWARM METAMATERIALS FOR INFORMATION DISPLAY, MEMORY, AND ENCRYPTIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 679,925, filed on August 6, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates to magnetoactive devices including magnetoactive multiphasic (e.g., Janus biphasic) particles (MAJPs) configured to selectively exhibit a swarming pattern when a magnetic force field is applied, suitable for displays, memory, and encryption. The present disclosure also relates to methods of forming a swarming pattern in such magnetoactive materials.BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] A variety of external field responsive materials have been developed for non- emissive display functions, using physical changes in the material and incoming environmental light to display information. Unlike traditional emissive displays, which use a front light or a backlight, such as light-emitting diodes (LEDs) or liquid crystal displays (LCDs), non-emissive displays do not require a dedicated light source and use only reflected ambient light instead. As a result, they have near- zero power consumption, are highly energy-efficient, have high contrast, wide viewing angles, flexibility, and overall better readability and performance in a wide range of environmental conditions, which makes them very attractive for use in portable and wearable devices. Common actuation methods in non-emissive display technologies include thermochromic (color change with temperature), electrochromic (color change with applied current through electrochemical reactions), electrophoretic / magnetophoretic (moving and rotating charged pigment particles in suspension with electric or magnetic fields), electrowetting (controlling the wetting of dyed solvents under an electric field), photochromic (colloidal phase segregation upon illumination), and mechanochromic mechanisms (based on structural coloration and deformation of photonic crystals), which have been driven by the development of new responsive materials, methods of actuation, and engineered functional particles. However, despiteAttorney Docket No. 2115-008421-WO-POA recent advances, most non-emissive displays have limited functionality and exhibit simple synchronous behavior with global on / off transitions, are limited by the arrangement of electrodes with fixed boundaries, and overall lack flexibility, reconfigurability, and complexity in the displayed information.

[0005] For example, earlier colored nanoparticles responsive to an external force field, such as magnetism, were limited in display capabilities. Such nanoparticles all globally responded to the applied field in the same way, for example, rotating from a first side to a second side and having a binary response (e.g., “on” and “off’). Thus, it was not possible to independently manipulate selective particles or to induce swarming behavior. Further, any visible patterns defined by the particles occur where the particles physically occupy a predefined shape (e.g., a patterned opening / reservoir in a substrate that holds the particles). Thus, only predefined patterns could be used and displays were not flexible or dynamic. Additionally, many nanoparticles were too small to establish highly visible contrast for a human observer.

[0006] Metamaterials and metasurfaces, engineered structures with periodic arrangements of minimal building blocks, have been increasingly gaining interest to embody intelligence (processing and display of complex information) in responsive physical constructs. Particularly, mechanical metamaterials have shown exciting potential in performing computing abstractions in physical systems, such as mechanical memory for information storage, physical mechanologic (from Boolean functions to integrated circuitry), and encryption. However, architected mechanical devices and responsive structures rely on compliant mechanisms (folding, bending, buckling, etc.) to achieve predefined states, which are difficult to miniaturize due to limitations in distributed actuation mechanisms at small scales, resulting in rather large structures with limited portability. Furthermore, metamaterials are often designed to fulfill a specific task with predefined target transitions from an initial state to a fixed final output configuration, with limited reconfigurability from a specific starting design. Instead of encoding information in the architected structure only, engineering these functions through multifunctional materials presents new opportunities for wide-spectrum programmability, miniaturization, and reconfigurability in metamaterials for performing advanced display and computing functions without compromising the device design space.

[0007] It would be desirable to develop metamaterials responsive to external force fields having nanoscale resolution with high flexibility, for example, for non-emissive displays having extensive functionality, reconfigurability, and complexity in the displayed information.Attorney Docket No. 2115-008421-WO-POASUMMARY

[0008] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0009] In certain aspects the present disclosure relates to a magnetoactive material comprising a plurality of multiphasic magnetoactive particles configured to selectively exhibit a swarming pattern when a magnetic force field is applied. Each particle of the plurality of multiphasic magnetoactive particles comprises a first phase comprising a first colorant and at least one additional phase distinct from the first phase. In this manner, each particle has optically distinct phases. Further, at least one of the first phase or the at least one additional phase comprises a material capable of magnetization and receptive to the magnetic force field.

[0010] In one aspect, the material that is capable of magnetization is selected from the group consisting of: iron (III) oxide (Fe2O3), iron (II, III) oxide (FC3O4), neodymium-iron-boron (NdFeB), manganese ferrite (MnFe2O4), cobalt ferrite (CoFe2O4), nickel iron oxide (NiFe2O4), nickel-iron alloys, chromium dioxide (CrCE), iron platinum (FePt), barium ferrite (BaFe or BaFenOw), and combinations thereof.

[0011] In one aspect, the material that is capable of magnetization is ferromagnetic or superp aramagnetic .

[0012] In one aspect, the material capable of magnetization comprises a first material capable of magnetization that is ferromagnetic and a second material capable of magnetization that is superparamagnetic.

[0013] In one further aspect, the first material comprises neodymium-iron-boron (NdFeB).

[0014] In one further aspect, the second material comprises a superparamagnetic iron oxide nanoparticle (SPION).

[0015] In one aspect, the plurality of multiphasic magnetoactive particles has an average particle size of greater than or equal to about 300 micrometers to less than or equal to about 500 micrometers.

[0016] In one aspect, the swarming pattern is reconfigurable.

[0017] In certain other aspects, the present disclosure relates to a magnetoactive device comprising a magnetoactive component that comprises comprising a plurality of multiphasic magnetoactive particles. The multiphasic magnetoactive particles are configured to selectively exhibit a swarming pattern when a magnetic force field is applied. Each particle comprises a first phase comprising a first colorant and at least one additional phase distinct from the first phase. In this manner, each particle has optically distinct phases. Further, at least one of the first phase orAttorney Docket No. 2115-008421-WO-POA the at least one additional phase comprises a material capable of magnetization and receptive to the magnetic force field.

[0018] In one aspect, the magnetoactive device further comprises a magnetic component for selectively generating the magnetic force field directed towards the magnetoactive component. The magnetic force field is configured to induce swarming behavior in at least a portion of the plurality of the magnetoactive particles.

[0019] In one aspect, the material that is capable of magnetization is selected from the group consisting of: iron (III) oxide (Fe2O3), iron (II, III) oxide (FC3O4), neodymium-iron-boron (NdFeB), manganese ferrite (MnFe2O4), cobalt ferrite (CoFe2O4), nickel iron oxide (NiFe2O4), nickel-iron alloys, chromium dioxide (CrCh), iron platinum (FePt), barium ferrite (BaFe or BaFenOw), and combinations thereof.

[0020] In one aspect, the material capable of magnetization is ferromagnetic or superp aramagnetic .

[0021] In one aspect, the material capable of magnetization comprises a first material capable of magnetization that is ferromagnetic and a second material capable of magnetization that is superparamagnetic.

[0022] In one aspect, the first material comprises neodymium-iron-boron (NdFeB).

[0023] In one aspect, the second material comprises a superparamagnetic iron oxide nanoparticle (SPION).

[0024] In one aspect, the plurality of multiphasic magnetoactive particles has an average particle size of greater than or equal to about 300 micrometers to less than or equal to about 500 micrometers.

[0025] In one aspect, the swarming pattern is reconfigurable.

[0026] In one aspect, the magnetoactive component is a swarm cell having a chamber comprising a liquid and the plurality of multiphasic magnetoactive particles disposed therein.

[0027] In one aspect, the magnetoactive device is a portable device or a wearable device.

[0028] In one aspect, the magnetoactive component defines at least one bit of memory.

[0029] In one further aspect, the at least one bit of memory is selected from the group consisting of: non-volatile memory, semi- volatile memory, and volatile memory.

[0030] In one aspect, the magnetoactive device forms part of an encryption system and the swarming pattern is encrypted.

[0031] In one aspect, the magnetoactive component defines a portion of a display component and the magnetoactive device is a display device or an optical device.Attorney Docket No. 2115-008421-WO-POA

[0032] In one aspect, the swarming pattern has been encoded or imprinted by an initial magnetization process.

[0033] been encoded or imprinted by an initial magnetization process.

[0034] In yet other aspects, the present disclosure relates to method of forming a swarming pattern in a magnetoactive material. The method may comprise applying a magnetic force field to the magnetoactive material that comprises a plurality of multiphasic magnetoactive particles to exhibit a swarming pattern. Each particle comprises a first phase comprising a first colorant and at least one additional phase distinct from the first phase to define optically distinct phases. At least one of the first phase or the at least one additional phase comprises a material capable of magnetization, so that at least a portion of the plurality of multiphasic magnetoactive particles change position to define the swarming pattern.

[0035] In one aspect, only a first portion of the plurality of magnetoactive multiphasic particles define the swarming pattern during the applying of the magnetic force field, while a second portion of the plurality of magnetoactive multiphasic particles do not change position or exhibit other discernable characteristics during the applying of the magnetic force field to provide a visible contrast with the first portion of the plurality of multiphasic magnetoactive particles defining the swarming pattern.

[0036] In one aspect, the swarming pattern is reconfigurable.

[0037] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.DRAWINGS

[0038] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0039] FIGS. 1A-1E show fabrication of magnetoactive multiphasic particles (Janus particles (MAJPs)) and a display system according to certain aspects of the present disclosure. FIG. 1A shows electrohydrodynamic (EHD) co-jetting to fabricate bicomp artmental PEGA fibers with magnetic particles and white pigment (e.g., titanium dioxide), followed by micro sectioning to slice into biphasic cylinders. FIG. IB shows shape transformation from multiphasic (Janus or MAJP) cylinders to particles through surface energy minimization. FIG. 1C shows a flexible magnetoactive multiphasic particles (MAJP) swarm display system. FIG. ID shows magneticAttorney Docket No. 2115-008421-WO-POA actuation of MAJP swarms exhibiting two color states under opposed magnetic field. FIG. IE shows high contrast between the two swarm states.

[0040] FIGS. 2A-2D show properties and collective behavior of magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure. FIG. 2A shows MAJPs are composed of magnetic particles (SPIONs (a superparamagnetic material) and / or NdFeB (ferromagnetic material)) in one compartment, and white pigment (TiO2) in the other distinct compartment. SEM and EDS images show Ti and Fe in each respective compartment. FIG. 2B shows magnetic hysteresis loop of MAJPs with ferromagnetic NdFeB particles (FM), superparamagnetic iron oxide nanoparticles (SPIONs) (SPM), and hybrid systems (with both NdFeB and SPIONs). FIG. 2C shows magnetic remanence of MAJPs as a function of varying actuation fields, exhibiting different magnetization stabilities. FIG. 2D shows states (brown color percentage) of different MAJP swarms as a function of actuation magnetic fields.

[0041] FIGS. 3A-3C show selective actuation and switching behavior of magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure where swarms have responsive logic functions. FIG. 3 A shows selective switching behavior of MAJP swarms (SPM and hybrid) with 4 interchangeable 2-bit states by controlling the actuation magnetic field direction and intensity. FIG. 3B shows MAJP swarms with “AND” and “OR” logic gate functions based on the individual input state of each particle type. FIG. 3C shows an output state of “AND” and “OR” MAJP logic swarms.

[0042] FIGS. 4A-4E show swarming display and memory functions of magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure. FIG. 4A shows a MAJP swarm display with static patterns under preprogrammed structured magnetic fields. FIG. 4B shows a dynamic MAJP swarm display pattern under structured rotating fields. FIG. 4C shows semi-volatile and FIG. 4D shows non-volatile memory of structured display patterns, showing loss and conservation of encoded information respectively. FIG. 4E shows integration of a soft MAJP swarm display device on a glove, showing the recovery of encoded non-volatile information after mechanical agitation.

[0043] FIGS. 5A-5D show encoding and encryption of information in magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure. FIG. 5A shows complex patterns are generated with a XOR operation of non-volatile magnetic encoding field and a semi- volatile reading field. FIG. 5B shows encryption is achieved by (i) encoding the particles with an encryption key field (non-volatile writing) and (ii) applying a complementary decryption key field (semi-volatile reading). FIG. 5C shows encryption using aAttorney Docket No. 2115-008421-WO-POA single encryption key (single public message) and three different decryption keys reading different private messages. FIG. 5D shows encryption using multiple encryption keys (different public messages) and three different paired decryption keys reading the same private message.

[0044] FIG. 6 shows electrohydrodynamic (EHD) co-jetting to form bicompartmental PLGA fibers with magnetic particles and white pigment (e.g., titanium dioxide). The fibers are fabricated using electrohydrodynamic (EHD) co-jetting techniques, and are collected on a rotary drum. A high voltage was applied between the co-aligned needles and the collecting drum.

[0045] FIGS. 7A-7B show bicompartmental Janus fibers. In FIG. 7A, magnetoactive multiphasic (Janus) fibers have an average diameter of about 300 micrometers. The scale bar is 1 mm. In FIG. 7B, a clear boundary between the magnetic (brown - formed of PLGA polymer and SPIONs) and the pigment (white - formed of PLGA and titanium dioxide) compartments. The scale bar is 500 pm.

[0046] FIG. 8 shows steps (i) to (vi) for assembly of a swarm display cell according to certain aspects of the present disclosure. In step i), a silicone spacer is attached to a flexible PET film substrate to define a cell. In step ii), a suspension of magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure are transferred into a cell. At iii), the cell is sealed with a PET film on top. At iv), needles are inserted at opposite sides of the pouch. Next at v), water is injected from one needle and expels the air through the other needle until no air bubbles remain in the pouch. In step vi), the swarm display cell is resealed after removing the needles.

[0047] FIG. 9 shows particle size optimization for magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure. MAJPs with different sizes (average diameters of 400 micrometers, 350 micrometers, 250 micrometers, and 40 micrometers) were put in the pouches and exposed to distinct magnetic fields. MAJPs smaller than 300 micrometers (pm) showed lower color density and poor color contrast between states. The scale bar is 1 cm.

[0048] FIG. 10 shows magnetoactive multiphasic particles (Janus particles (MAJPs)) without initial pre-magnetization. Without an initial pre-magnetization step, all MAJP types oscillated around zero magnetization. Ferromagnetic (FM) MAJPs had the lowest magnetization, with hybrid (both ferromagnetic and superparamagnetic) and superparamagnetic (SPM) MAJPs increasing in magnetization respectively.

[0049] FIGS. 11A-11B shows particle orientation and synchronization. Ferromagnetic (FM) MAJPs do not align synchronously under a small field due to the small magnetic moment generated before the magnetization process, whereas hybrid MAJPs (having both ferromagneticAttorney Docket No. 2115-008421-WO-POA and superparamagnetic particles) align synchronously. FIG. 11A shows after magnetizing the particles at high fields, the magnetic remanences of the FM MAJPs do not align with the geometric main axis and therefore there is not synchronized alignment. FIG. 1 IB shows that the remanences of hybrid MAJPs align with the main axis, therefore exhibiting synchronized alignment.

[0050] FIGS. 12A-12C show magnetoactive multiphasic particles (Janus particles (MAJPs)) hybrid swarm color hysteresis with different compositions. FIG. 12A shows hybrid particles with 25% ferromagnetic particles to 75% a superparamagnetic iron oxide nanoparticles (SPIONs). FIG. 12B shows hybrid particles with 50% ferromagnetic particles to 50% SPIONs. FIG. 12C shows hybrid particles with 75% ferromagnetic particles to 25% SPIONs. Color switching hysteresis of hybrid MAJP swarms with varying FM:SPION ratio was characterized by measuring the dark (brown) color percentage under a cycling external magnetic field.

[0051] FIGS. 13A-13C show magnetoactive multiphasic particles (Janus particles (MAJPs)) swarm color hysteresis with different particle types. Color switching hysteresis of FIG. 13A ferromagnetic (FM), FIG. 13B shows superparamagnetic (SPM), and FIG. 13C shows hybrid MAJPs as a function of cycling field, exhibiting characteristic switching behaviors and stabilities.

[0052] FIG. 14 shows interchangeable state transitions in 2-bit magnetoactive multiphasic particles (Janus particles (MAJPs)) swarm system according to certain aspects of the present disclosure. The device is composed of a SPM and a hybrid MAJP swarms next to each other, each swarm corresponding to 1 bit. Under the same global external field, the system can display 2-bit information as a function of field intensity and direction. Due to their different magnetic stabilities, the magnetization of SPM and hybrid MAJPs can be parallel or anti-parallel, leading to four color states based, (dashed lines represent transitions at lower fields without rewriting SPM MAJPs, whereas solid lines represent transitions at higher fields by rewriting SPM MAJPs).

[0053] FIG. 15 shows hybrid magnetoactive multiphasic particles (Janus particles (MAJPs)) having two distinct materials capable of magnetization according to certain aspects of the present disclosure with opposite magnetization directions. MAJP swarms of hybrid particles are shown, each pre-magnetized in opposite directions. Due to their different magnetization, they rotate and align opposite of each other under the same global actuation field.

[0054] FIG. 16 shows swarm color calibration as a function of magnetoactive multiphasic particles (Janus particles (MAJPs)) composition. Swarms with solid titanium dioxide (TiO2) particles and varying composition of SPM MAJPs exhibit a constant white color in their OFF states and a white-brown transition with increasing MAJP density.

[0055] FIGS. 17A-17B show a swarm color perception test. FIG. 17A shows a swarm color state (brown state density) of a SPM MAJP swarm with varying composition in OFF andAttorney Docket No. 2115-008421-WO-POAON states. FIG. 17B shows a human color perception test (n=47) that indicates a perceived consensus threshold of 45% between the ON-OFF switching.

[0056] FIG. 18 shows a design of magnet arrays for the generation of programmable structured fields. A 3D-printed holder and a permanent magnet array was used to generate a heterogeneously structured magnetic field, which is controlled by the pattern and the orientation of the permanent magnets. The magnetic field design can be visualized by a magnetic field viewer screen, and can further actuate the MAJP swarms into predesigned patterns.

[0057] FIGS. 19A-19C show dynamic magnetoactive multiphasic particles (Janus particles (MAJPs)) swarming displays according to certain aspects of the present disclosure. FIG. 19A shows a rotating permanent magnet array configured to an arrow pattern was used to dynamically actuate the swarm and display a rotating arrow pattern. Sliding stamps with permanent magnet arrays display. The scale bar is 5 mm. FIG. 19B shows moving text (“UM”). The scale bar is 5 mm. FIG. 19C shows numbers (Euler’s number e = 2.7183). The scale bar is 5 mm. Images correspond to multiple timepoints to show the programmed dynamic patterns.

[0058] FIG. 20 shows a graphic encryption mechanism according to certain aspects of the present disclosure. A graphic XOR encryption process is done by first encoding the encrypted message to the display, followed by reading the information using a decryption key. Here, to communicate a private message of “o”, a blank swarm is encoded with an encryption key field with a public message of “x” when read with a homogeneous field without the proper reading key. Only when the unique complementary decryption key field is applied, the private message can be read. However, without the proper encrypted public message, the reading message of the decrypted key on a blank display is a meaningless graphic pattern.

[0059] FIG. 21 shows multiple private messages delivered using a single encryption key. One encryption key field can be paired with multiple decryption keys to deliver different private messages. Here, with the same “public” message of “x” and multiple paired decryption keys, private messages of, can be delivered. Without the proper encrypted “public” message, the reading message of the decrypted key on a blank display is meaningless graphic pattern. The scale bar is 5 mm.

[0060] FIG. 22 shows a single private message delivered through multiple encryption / decryption keys according to certain aspects of the present disclosure. One private message can be delivered using different encryption keys with different “public” encoded messages. Here, blank swarms are encoded with “public” messages ofwhich are then decoded using their paired decryption keys to display the same private message of “o.” The scale bar is 5 mm.Attorney Docket No. 2115-008421-WO-POA

[0061] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.DETAILED DESCRIPTION

[0062] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0063] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although the open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of’ or “consisting essentially of.” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and / or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and / or process steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and / or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and / or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.Attorney Docket No. 2115-008421-WO-POA

[0064] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.

[0065] When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0066] Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and / or sections, these steps, elements, components, regions, layers and / or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

[0067] Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.

[0068] Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about”Attorney Docket No. 2115-008421-WO-POA actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. For example, “about” may comprise a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in certain aspects, optionally less than or equal to 0.1%.

[0069] In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.

[0070] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0071] The present disclosure pertains to a magnetoactive material that may be used in a magnetoactive device or system, which may include a variety of devices that are configured and activated by application of a magnetic field. By way of non-limiting example, these magnetoactive materials may be used in a wide variety of applications, including for personal security, defense, anti-counterfeiting, camouflage, soft robotics, and human-robot interaction, among others. For example, the magnetoactive materials may be used in wearable devices, including fashion accessories, portable devices, optic and display devices, computing devices and memory (volatile, semi- volatile, and non-volatile memory), smart paints, camouflage, tattoos, QR codes, (food) packaging, physical unclonable functions, credentials, encryption, and the like. For example, in certain variations, the magnetoactive device may be an optical device or display, such as a non-emissive display. An optical device may be used in a variety of applications, such as visual, optical, and / or electronic displays, including as displays, such as displays for wearable and portable devices, panels, screens, monitors, sensors, electronic paper, and the like, by way of nonlimiting example. The optical device defines optic features in one or more swarming patterns that can be externally observed, such as a character or pixel, by way of non-limiting example. In other aspects, the magnetoactive device may be part of a computing or digital communication system, for example, a bit or bits of reconfigurable and / or non-volatile memory.

[0072] In various aspects, the magnetoactive material is incorporated into a device or system that comprises a magnetoactive component. The magnetoactive component comprises a plurality of multiphasic magnetoactive solid particles (also referred to herein as “Janus particles”) configured to selectively exhibit a swarming pattern when a magnetic force field is applied. AAttorney Docket No. 2115-008421-WO-POA swarming pattern can be determined by controlling the swarming behavior of at least a portion of the plurality of multiphasic magnetoactive particles, where the particles collectively exhibit a cumulative state or property that the individual particles do not exhibit. Notably, a swarming pattern can be achieved with the plurality of multiphasic magnetoactive solid particles on a flat or planar substrate and by control of at least a portion of the particles via a magnetic field alone and does not require a template, reservoir or other physical pattern that the particles are disposed in to generate a visible pattern. Further, as described above, swarming behavior may be distinguished from previous control of multiphasic colored particles, where the magnetic field was only capable of inducing global binary positioning / flipping of the particles. In this manner, the application of a magnetic field alone can create visually distinct patterns for select magnetoactive particles by inducing swarming behavior.

[0073] In various aspects, each multiphasic magnetoactive solid particle comprises a first phase comprising a first composition and at least one additional phase distinct from the first phase. Each solid particle has optically distinct phases. In certain aspects, the first phase may comprise a first colorant to visually distinguish it from the second phase (or further additional phases), which may or may not have a second colorant(s). As used herein, “multiphase” or “multiphasic” means that at least two phases herein occupy separate but distinct physical spaces to form the particle shape defining distinct “compartments.” By the term “phase” it is meant that a portion, domain, or region of a particle is chemically and / or physically distinct from another portion, domain, or region of the particle, for example a phase may have one average composition distinct from another phase having a different average composition. Each respective phase optionally occupies a spatially discrete region or compartment of the particle. Such phases may be in direct contact with one another (e.g., they are not separated by a barrier and they are not emulsified or mixed to any significant degree). In certain aspects, each respective phase of the multiphasic particle is exposed to an external environment, thus providing exposure of the respective phase surfaces of the multiphasic particle to an external environment. The exposure of each respective surface of each phase provides enhanced environmental interface and optimum visibility for optical applications. In certain variations, the multiphasic magnetoactive particles may comprise from two to eight distinct phases.

[0074] In certain aspects, the respective phases are visible to the human eye and / or to an electronic or automated sensor. In other aspects, a plurality of similar multiphasic colorant particles may generate a net visual effect when similar phases are grouped together or swarm in a pattern to exhibit a color field (so that the individual multiphasic particle phases may not necessarily be discernable to the human eye). Such a particle may comprise at least one colorantAttorney Docket No. 2115-008421-WO-POA and at least two distinct phases, such that the respective phases occupy distinct regions or domains in the component, which are visually, optically, and / or physically distinct from one another. Further, in accordance with various aspects of the present disclosure, at least one of the first phase or the additional phase(s) comprises a material capable of magnetization and receptive to the magnetic force field. A material that is capable of magnetization may exhibit magnetism, paramagnetism, superparamagnetism, electromagnetism, ferromagnetism and / or ferrimagnetism, by way of example. A magnetic material has permanent magnetic poles, whereas a paramagnetic material has the ability to have induced magnetic poles in the presence of an applied external magnetic field. For example, superparamagnetism is a form of induced magnetism exhibited by small ferromagnetic or ferrimagnetic nanoparticles, for example, generally having an average particles size of less than about one hundred nanometers. At these small sizes, the nanoparticles may be considered single-domain particles allowing macro- spin approximation, where magnetization of the nanoparticles is approximated as a consolidated magnetic moment by summing the individual magnetic moments of each constituent atom. Ferromagnetism is a permanent and strong magnetic force that occurs for certain materials comprising iron, nickel, and cobalt and is further enhanced by neodymium. Ferrimagnetism is generally weaker than ferromagnetism, as magnetic microdomains in the material are oriented in different directions, and may occur in within iron (II, III) oxide (FeaC ).

[0075] The multiphasic magnetoactive solid particles of the present disclosure are thus responsive to an applied magnetic force field and therefore have the ability to swarm and modulate the optical appearance of the particles based on the magnetic field applied. The optical appearance may thus be controlled in localized regions to define distinct patterns via swarming. In certain aspects, the magnetoactive device further includes a magnetic component for selectively generating the magnetic force field directed towards the magnetoactive component, where the magnetic force field is configured to induce swarming behavior in at least a portion of the plurality of the magnetoactive solid particles.

[0076] Suitable multiphasic particles comprise a first phase and at least one additional phase distinct from the first phase, where the first phase optionally comprises a first colorant, while the one or more additional phases does not. In this manner, the multiphasic particle has optically distinct phases. In certain variations, the one or more additional phases may comprise a second colorant distinct from the first colorant. In certain embodiments, the multiphasic particles may comprise one or more additional phases, for example, a third phase having a third colorant distinct from the first and second colorants. Further, the present disclosure contemplates one or more distinct multiphasic particles in the plurality of particles. In such embodiments, the pluralityAttorney Docket No. 2115-008421-WO-POA of multiphasic particles includes a first multiphasic particle (having the first phase and one or more additional phases), as well further comprising at least one additional distinct multiphasic particle.

[0077] At least one of the first phase and the at least one additional phase of the multiphasic particles comprises a material receptive to a force field. Examples of force fields include magnetic fields, electric fields, pressure, sonication, light, and the like. However, in various aspects, the multiphasic particles comprise at least one material that is receptive to a magnetic force field providing a magnetoactive particle, such as the categories of magnetic materials described above. Notably, the multiphasic particles may be receptive or responsive to multiple force fields, such as a magnetic field and electric field, by way of non-limiting example. “Receptive” means that the material has a physical response when in the presence of an external force field, for example, changing position, shape, or other discernable characteristics in the presence of a magnetic field. Further, the material is selected for inclusion in one or more phases of the multiphasic particle so that it is receptive to an external field, for example, the magnetic field, and exhibits a collective and common response shared with at least a portion of the other particles to exhibit swarming behavior.

[0078] Therefore, in certain embodiments, the magnetoactive device may further include one or more magnets that generate the force field transmitted to the magnetoactive component. Thus, in the presence of the magnetic force field, the magnetoactive component reversibly exhibits at least a portion of the plurality of magnetoactive particles having a first collective state. Where the magnetoactive component is a display, this first collective state may correspond to a first color within the swarm pattern, for example. Furthermore, the absence or modification of the force field can modify the orientation of particles to exhibit a second distinct state that differs from the first optical state, like a second distinct color, for example. As noted above, the magnetoactive device may include components for applying other force fields in addition to a magnetic force field, such as an electric field induced by a power or voltage source applied to the particles.

[0079] In various aspects, the multiphasic magnetoactive particles have visually distinct phases and are anisotropic, therefore such multiphasic magnetoactive particles are capable of being oriented in select regions (e.g., in a region corresponding to an optic or otherwise detectable feature). Where the magnetoactive component is part of a display for a display device, the particles can be oriented to create an optic feature that can exhibit a first optical state in the presence of an external magnetic force field, where a portion of the plurality of particles are oriented in a first direction to define a swarm pattern. When the external magnetic force field is altered (for example, with respect to quantity or gradient, polarity, or being switched on or off), at least a portion of theAttorney Docket No. 2115-008421-WO-POA plurality of particles are oriented in a second distinct direction so that the magnetic force field induces a second optical state that is optically distinct from the first optical state. By way of nonlimiting example, the first optical state may correspond to a first color and the second optical state may correspond to a second color.

[0080] In certain variations, the magnetoactive component comprises a first side and a second side opposite to the first side. One or more magnets may be disposed adjacent to a first side of the magnetoactive component to induce the first state defining a first swarm pattern, such as a first optical state. If such magnet(s) are disposed adjacent to a second side of the magnetoactive component, it will induce a second state distinct from the first state, for example, the absence of the first swarm pattern or a distinct second swarm pattern. As will be appreciated further by the ensuing discussion, the multiphasic magnetoactive solid particles may be induced to have more swarm patterns than just two, in other words multiple distinct swarm patterns. In certain variations, the magnet(s) may be moved relative to the magnetoactive component or alternately the magnetoactive component may be moved relative to the magnet(s).

[0081] In other variations, the present disclosure provides methods of reversibly inducing a swarm pattern in at least a portion of the plurality of multiphasic magnetoactive solid particles, for example, for an optic display in an optical device. Such a method may optionally include transmitting a magnetic force field to a magnetoactive component that comprises a plurality of multiphasic magnetoactive solid particles. Notably, the plurality of multiphasic magnetoactive solid particles encompasses the use of one type of multiphasic particle, but may also include one or more distinct multiphasic magnetoactive particles. The multiphasic magnetoactive particle comprises a first phase and at least one additional phase distinct from the first phase. The first phase may comprise a first colorant, while the one or more additional phases are optically distinct and optionally may comprise a second colorant distinct from the first colorant. In this manner, the magnetoactive multiphasic particles have optically distinct phases. Further, as discussed above, in certain embodiments, the multiphasic particles may comprise one or more additional phases, for example, a third phase having a second or third colorant distinct from the first and / or second colorants. At least one phase (either the first phase and the at least one additional phase) comprises a material capable of magnetization and thus receptive to the magnetic force field, wherein during or after the transmitting of the magnetic force field the magnetoactive component reversibly exhibits a first state. The method may include generating the external force field and transmitting it to the magnetoactive component. For example, an external magnet can be used to generate the magnetic force field transmitted to the magnetoactive component.Attorney Docket No. 2115-008421-WO-POA

[0082] The magnetoactive component, such as a display component, comprises a first side and a second side opposite to the first side. The force field generator, like one or more magnets, is placed adjacent to a first side of the magnetoactive component to induce at least a portion of the plurality of multiphasic magnetoactive solid particles to have a first swarm pattern in the first state. In certain embodiments, the force field generator may be placed adjacent to the second side of the magnetoactive component to induce a second state distinct from the first state. Alternatively, the force field generator may have the magnetic field modified and placed adjacent to a first side of the magnetoactive component to include a second state of at least a portion of the plurality of multiphasic magnetoactive solid particles. The force field generator can then be placed adjacent to the first side and repeated, as needed, because the first and second states are reversible conditions, depending on the orientation of the magnetic field and the magnetophoretic effects on the display component. It should also be noted that the present disclosure is not limited to only first and second states, but may include a multitude of distinct states that are achieved by altering the orientation of the particles (where the particles may have three or more optically distinct phases and / or by using a mixture of distinct multiphasic particles in a single optic feature) by controlling the quantity, direction, and / or gradient of the force field applied. Notably, multiphasic particles may be used that are responsive to distinct force fields, for example, one particle may be responsive to a magnetic field, where a distinct particle may be responsive to electric charge, for example.

[0083] In various aspects, methods of making multiphasic microparticles and nanoparticles are described as being formed in U.S. Patent No. 7,947,772 to Lahann et al. and U.S. Patent No. 9,482,861 to Lahann et al., which are commonly assigned to the assignee of the present application and the relevant portions of which are herein incorporated by reference in their entireties. Thus, electrified jetting methods to form such multiphasic particles will only be discussed briefly below. In certain aspects, one or more phases of the multiphasic particles optionally include a material capable of magnetization, making the multiphasic particle further having one or more colorants suitable for use as a pixel for an optic display, an encryption system, or for use as a bit in a computing or communication device, for example. In yet other aspects, a multiphasic particle optionally includes a component or have one or more exposed phase surfaces that enable relative orientation and self-assembly of the particles on a surface or substrate.

[0084] The plurality of magnetoactive solid particles are anisotropic possessing two or more distinct phases, at least one of which may comprise a colorant; therefore, having two or more optically distinct phases. In various aspects, multiphasic components suitable for use with the present technology, such as biphasic or “Janus” micro-particles, comprise one or more colorantsAttorney Docket No. 2115-008421-WO-POA in addition to one of more materials capable of magnetization. Such multiphasic colorant particles can be made in a process that uses electrified jetting techniques to fabricate polymer-based fibers or particles. In certain aspects, such multiphasic magnetoactive solid particles may be microparticles or nanoparticles.

[0085] A “microparticle” may have a variety of shapes or morphologies, however, generally has at least one spatial dimension that is less than about 1,000 micrometers (1 mm), optionally less than 500 micrometers, optionally less than 250 micrometers, optionally less than 100 micrometers, optionally less than about 75 micrometers, optionally less than about 50 micrometers, optionally less than about 25 micrometers, optionally less than about 20 micrometers, optionally less than about 10 micrometers (i.e., 10,000 nm), optionally less than or equal to about 5 micrometers (i.e., 5,000 nm) and in certain aspects, optionally less than about 1 micrometers (i.e., 1,000 nm). Of course, as appreciated by those of skill in the art, other dimensions of the particle may be significantly greater than the dimension falling within the nano or micro range.

[0086] A “nanoparticle” may have at least one spatial dimension that is less than about 10 pm (i.e., 10,000 nm). The term “nano-sized” or “nanometer-sized” is generally understood by those of skill in the art to mean less than about 10 pm (i.e., 10,000 nm), optionally less than about 1 pm (i.e., less than about 1,000 nm), optionally less than about 0.5 pm (i.e., 500 nm), and in certain aspects, less than about 200 nm.

[0087] In certain aspects, a plurality of multiphasic magnetoactive solid particles are microparticles and have at least one spatial dimension, for example, an average particle size / diameter, of greater than or equal to about 250 micrometers to less than or equal to about 500 micrometers, optionally greater than or equal to about 300 micrometers to less than or equal to about 500 micrometers, optionally greater than or equal to about 300 micrometers to less than or equal to about 450 micrometers, and optionally greater than or equal to about 325 micrometers to less than or equal to about 375 micrometers, for example, about 350 micrometers. Such particle sizes are particularly suitable for defining optical features discernable by the human eye, while providing other performance advantages in the magnetoactive component of a magnetoactive device.

[0088] As mentioned above, the microparticle may have a variety of geometries or morphologies, including, by way of non-limiting example, spheres (substantially spherical shapes), ovals, discs, ellipsoids, rods / cylinders, toroids, polygons, rectangles, cones, fibers, and the like. As will be described further below, in certain variations, a microfiber may be formed by electrohydrodynamic jetting and then cut at regular intervals to initially form cylinders.Attorney Docket No. 2115-008421-WO-POAMicrofibers have an elongated axial dimension that is substantially longer than the other dimensions of the microfiber. However, after the microfiber is cut, the cylinders will transform to spheres after the cutting process.

[0089] In certain aspects, the plurality of multiphasic magnetoactive particles comprise materials in a solid phase or a semi-solid phase.

[0090] Multiphasic magnetoactive particles made in accordance with the electrohydrodynamic processes described above optionally have a wide range of optical properties. The optical properties of the multiphasic particles are generally related to the type and concentration of colorant molecules in the respective compositions forming the phases or the optical properties of the exposed surface of one or more phases. As used herein, the term “colorant” is meant to include without limitation any material that provides an optical or visual effect, tint, or color to a material. The term is meant to include a single material or a mixture of two or more colorant materials. By way of example, two similar phases may include a first phase also comprising a colorant (e.g., pigments, dyes, particles) and a second phase that may lack any of the colorant, may have different average composition of the colorant, or may have an additional or alternative colorant to provide a visually or optically distinct effect. Alternately, the two phases may vary in composition and / or colorants and thus may include multiple visually or optically distinct phases.

[0091] Suitable colorant materials for use in accordance with the present disclosure include, but are not limited to, dyes, pigments, and polymers. A “pigment,” is generally an inorganic or organic, colored, white or black material that is usually substantially insoluble in solvents. A “dye,” unlike a pigment, is generally soluble in a solvent or carrier. Pigments may be selected to have a particle size suitable for an application, for example, a maximum particle size that is small enough to avoid clogging of nozzles or capillaries during formation and of a smaller particle size than the particle dimensions. In certain aspects, the pigments have minimal deviation in particle size, i.e. have a narrow particle size distribution. Other suitable colorants include polymers, which may also form a structural component material of the multiphasic particles.

[0092] A first colorant present in the first phase and any additional optional colorants present in the second or further additional phases are optionally independently selected from the group of materials consisting of: low-molecular weight dye, a laser dye, a textile dye, a paint dye, a paint pigment, a coating dye, a coating pigment, a plastic colorant, a metal colorant, a ceramic colorant, a fluorescent dye, a phosphorescent dye, a natural dye, a polymeric dye, inorganic pigment, an organic pigment, and combinations thereof. In certain variations, one or more colorants may be selected from materials including a pearlescent pigment, a metallic flakeAttorney Docket No. 2115-008421-WO-POA pigment, a cholesteric liquid crystal (CLC) pigment, an ultramarine pigment, a fluorescent pigment, a phosphorescent pigment, an inorganic pigment, a carbon black pigment, a natural pigment, an organic pigment, a mixed metal oxide pigment, an iron oxide pigment, a titanium dioxide pigment, a metal colorant, a ceramic colorant, a plastic colorant, an organic azo pigment, an organic polycyclic pigment, a dyeing lake pigment, an azine pigment, a direct dye, a vat dye, a sulfur dye, a reactive dye, a disperse dye, an acid dye, an azoic dye, a synthetic dye, a basic dye, a laser dye, a polymeric dye, a natural dye, a fluorescent dye, and / or a phosphorescent dye. The first phase and the at least one additional phase each have an exposed surface and form a multiphasic particle having optically distinct exposed surfaces.

[0093] A red colorant emits electromagnetic radiation at a wavelength of about 625 nm to 740 nm; orange at about 590 nm to about 625 nm; yellow at about 565 nm to about 590 nm; green at about 520 nm to about 565 nm; blue or cyan at about 500 nm to about 520 nm; blue or indigo at about 435 to about 500 nm; and violet at about 380 nm to about 435 nm. A white colorant (achromatic colorant) generally reflects or emits a combination of all the colors of the visible light spectrum. A “substantially white” colorant gives the appearance of and / or is perceived as a white or grey shade, although the colorant may not exhibit true achromaticity.

[0094] Suitable dye colorants include direct dyes (for substrates such as cotton, cellulosic and blended fibers), vat dyes (for substrates such as cotton, cellulosic and blended fibers), sulfur dyes (for substrates such as cotton and cellulosic fiber), organic pigments (for substrates such as cotton, cellulosic, blended fabrics, paper), reactive dyes (for substrates including cellulosic fiber and fabrics), disperse dyes (for synthetic fiber substrates), acid dyes (for wool, silk, paper, synthetic fibers, and leather substrates), azoic dyes (for printing inks and pigments), synthetic dyes, basic dyes (for silk, wool, and cotton substrates), fluorescent dyes, and phosphorescent dyes.

[0095] Suitable pigment colorants include by way of non-limiting example, pearlescent, metallic flake, cholesteric liquid crystal (CLC) pigments, ultramarine pigments, effect pigments, fluorescent pigments, phosphorescent pigments, inorganic pigments, carbon black pigments, natural pigments, organic pigments, mixed metal oxide pigments, iron oxide pigments, titanium dioxide pigments, organic azo pigments (such as azo lake pigments, insoluble azo pigments, condensed azo pigments, and chelate azo pigments), organic polycyclic pigments (such as phthalocyanine based pigments, anthraquinone based pigments, perylene based pigments, perinone based pigments, indigo based pigments, quinacridone based pigments, dioxazine based pigments, isoindolinone based pigments, quinophthalone based pigments, and diketopyrrolopyrrole (DPP) based pigments), dyeing lake pigments (such as lake pigments ofAttorney Docket No. 2115-008421-WO-POA acid or basic dyes), azine pigments; and the like. Further, suitable colorants may include surface- treated pigments.

[0096] In certain aspects, synthetic colorants include polymers, which may serve as a structural material of the particle, as well as a colorant. One suitable and non-limiting example is the class of poly(aryleneethynylene) (PAE) polymers, which are conjugated and stable solid polymers that can fluoresce in orange, yellow, green, and blue ranges, for example. Suitable examples of PAE fluorescent polymers include poly(p-phcnylcnc), poly(p-phcnylcnccthynylcnc) (PPE) or poly(p-phcnylcncvinylcnc) and derivatives thereof, including those derivates having alkyl, alkyl phenyl, and alkoxy groups such as grafted PPE and dioctyl-PPE, or ternary benzothiadiazole-co-alkyne-co-alkyne substituted backbones. Other suitable conjugated polymers include polythiophene and polyaniline, by way of example.

[0097] Particularly suitable colorants for the multiphasic particles include low-molecular weight dyes, such as laser dyes, textile dyes, paint dyes and pigments, coating dyes and pigments, plastic colorants, metal colorants, ceramic colorants, fluorescent or phosphorescent dyes, fluorescent polymers, natural dyes, polymeric dyes, inorganic or organic pigments, or mixtures thereof.

[0098] Hence, a variety of colorants are known to those of skill in the art and is suitable for use in accordance with the present disclosure. By way of non-limiting example, suitable colorants include Color Index (C.I.) (published by the Society of Dyers and Colourists): C.I. Pigment Yellow 14, 93, 95, 109, 110, 120, 128, 138, 139, 151, 154, 155, 173, 180, 185 and 193, C.I. Direct Yellow 8, 9, 11, 12, 27, 28, 29, 33, 34, 35, 37, 39, 41, 42, 44, 50, 53, 58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110, 130, 132, 142, 144, 161, 163; C.I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76, 79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218, 219, 222, 227; C.I. Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42; C.I. Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40; C.I. Pigment Orange 13, 16, 34, 36, 43, 61, 63 and 71; C.I. Pigment Green 7, C.I. Pigment Red 101, 108, 122, 202, 254; C.I. Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81,83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 221, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243, 247; C.I. Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127, 128, 131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299, 301, 305, 336, 337, 361, 396, 397; C.I. Reactive Red 3, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40, 41, 43, 45, 49, 55; C.I. Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45, 46; C.I. Pigment Blue 27, 29, 15:1, 15:2, 15:3, 15:4, 15:6, 17:1; C.I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80,84, 86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168, 189, 192, 193, 194, 199, 200, 201,Attorney Docket No. 2115-008421-WO-POA202, 203, 207, 211, 213, 214, 218, 225, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289, 291; C.I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112, 113, 120, 127:1, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247, 258, 260, 264, 271, 277, 278, 279, 280, 288, 290, 326; C.I. Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25, 26, 27, 28, 29, 38; C.I. Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62, 65, 66, 69, 71; C.I. Pigment Violet 19, 23 and 33; C.I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100, 101; C.I. Acid Violet 5 34, 43, 47, 48, 90, 103, 126; C.I. Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34; C.I. Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37, 39, 40, 48; C.I. Pigment Black 7; C.I. Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97, 108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166, 168, 173, 199; C.I. Acid Black 7, 24, 29, 48, 52:1, 172; C.I. Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32, 34; C.I. Basic Black 7, and 8; and C.I. Pigment White 4, , C.I. Pigment White 18, and C.I. Pigment White 21.

[0099] In ink applications, a colorant set that provides full-color complement for printing images, includes colorants for cyan, magenta, yellow, and black or “key” (CMYK). For example, C.I. Pigment Yellow 138, 151, 154, 180 and 185 may be used as the yellow colorant in ink applications. Other examples of exemplary yellow dyes suitable for use in the multiphasic particles include aryl- and heterylazo dyes having phenols, naphthols, anilines, pyrazolones, pyridones or open chain active methylene compounds as coupling components, azomethine dyes having open active chain methylene compounds as coupling components, methine dyes such as benzylidene dye and monomethine oxonol dye, and quinone dyes such as naphthoquinone dye and anthraquinone dye. Other examples of the yellow dye employable herein include quinophthalone dyes, nitro-nitroso dyes, acridine dyes, and acridinone dyes. Such dyes typically exhibit yellow color when the chromophore undergoes partial dissociation. The counter cation in this case may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion, or a polymer cation having such cations as partial structure.

[0100] Examples of magenta colorants, suitable for use in multiphasic particles used in ink applications, include C.I. Pigment Red 122 and 202, 254, C.I. Pigment Violet 19; aryl- and heterylazo dyes having phenols, naphthols or anilines as coupling components, azomethine dyes having pyrazolones or pyrazolotriazoles as coupling components, methine dyes such as arylidene dye, styryl dye, melocyanine dye and oxonol dye, carbonium dyes such as diphenylmethane dye, triphenylmethane dye and xanthene dye, quinone-based dyes such as naphthoquinone, anthraquinone and anthrapyridone, and condensed polycyclic dyes such as dioxazine dye. Again, such dyes typically exhibit magenta color when the chromophore undergoes partial dissociation.Attorney Docket No. 2115-008421-WO-POAThe counter cation in this case may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion, or a polymeric cation having such cations as partial structure.

[0101] In yet other examples, cyan colorants for the multiphasic particles are optionally selected from C.I. Pigment Blue 15; azomethine dyes such as indoaniline dye and indophenol dye, polymethine dyes such as cyanine dye, oxonol dye and melocyanine dye, carbonium dyes such as diphenylmethane dye, triphenylmethane dye and xanthene dye, phthalocyanine dyes, anthraquinone dyes, aryl- and heteryl azo dyes having phenols, napthols or anilines as coupling components, and indigo-thioindigo dyes. These dyes typically exhibit cyan color when the chromophore undergoes partial dissociation. The counter cation in this case may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion, or a polymeric cation having such cations as partial structure.

[0102] For black (“K”) colorants suitable for use in ink applications, an acidic or neutral pigment of C.I. Pigment Black 7, carbon black, magnetite, and aniline black and / or polyazo dye are all suitable options.

[0103] In certain embodiments, colorants are optionally selected which are approved for incorporation into a food, drug, or cosmetic by a regulatory agency, such as FD&C or D&C pigments and dyes approved by the Federal Drug Administration (FDA) for use in the United States. Food-safe and / or cosmetically acceptable colorants among those useful herein include FD&C Red No. 3 (sodium salt of tetraiodofluorescein), Food Red 17, disodium salt of 6-hydroxy- 5-{(2-methoxy-5-methyl-4-sulphophenyl)azo]-2-naphthalenesulfonic acid, Food Yellow 13, sodium salt of a mixture of the mono and disulphonic acids of quinophtalone or 2-(2-quinolyl) indanedione, FD&C Yellow No. 5 (sodium salt of 4-p-sulfophenylazo-l-p-sulfophenyl-5- hydroxypyrazole-3 carboxylic acid), FD&C Yellow No. 6 (sodium salt of p-sulfophenylazo-B- naphtol-6-monosulfonate), FD&C Green No. 3 (disodium salt of 4-{[4-(N-ethyl-p- sulfobenzylamino)-phenyl]-(4-hydroxy-2-sulfoniumphenyl)-methylene}- [l-(N-ethyl-N-p-sulfobenzyl)-A-3,5-cyclohexadienimine], FD&C Blue No. 1 (disodium salt of dibenzyldiethyl-diaminotriphenylcarbinol trisulfonic acid anhydrite), FD&C Blue No. 2(sodium salt of disulfonic acid of indigotin), and mixtures thereof in various proportions. In certain aspects, the colorant comprises a cosmetically and / or pharmaceutically acceptable water insoluble inorganic pigment, such as titanium dioxide, chromium oxide green, phthalocyanine green, ultramarine blue, ferric oxide, or a water insoluble dye lake. In certain embodiments, dye lakes include calcium or aluminum salts of an FD&C dye such as FD&C Green #1 lake, FD&C Blue #2 lake, D&C Red #30 lake and FD&C # Yellow 15 lake. In yet other embodiments, a whiteAttorney Docket No. 2115-008421-WO-POA colorant is used, for example titanium dioxide (TiCh), titanium dioxide coated mica, a mineral, or a clay. Notably, the material capable of magnetization included in the multiphasic nanoparticles may also serve as a colorant.

[0104] The amount of colorant included in each respective phase of the multiphasic particles will depend on the selection of the colorant and its properties as well as the desired hue, saturation, and value. In certain aspects, a sufficient amount of colorant is included to attain the desired color density or optical effect in the respective phase of the multiphasic particles. In certain aspects, the colorant is present in the respective phase at optionally less than or equal to about 95 weight %; optionally less than or equal to about 85 weight %; optionally less than or equal to about 75 weight %; optionally less than or equal to about 65 weight %; optionally less than or equal to about 55 weight % optionally less than or equal to about 50 weight %; less than or equal to about 45 weight %; optionally less than or equal to about 40 weight %; optionally less than or equal to about 35 weight %; optionally less than or equal to about 30 weight %; optionally less than or equal to about 25 weight %; optionally less than or equal to about 20 weight %; optionally less than or equal to about 15 weight %; optionally less than or equal to about 10 weight %; optionally less than or equal to about 5 weight %; optionally less than or equal to about 3 weight %; optionally less than or equal to about 1 weight %; and in certain aspects less than or equal to about 0.5 weight%. In certain aspects, each respective phase in the particle comprises about 0.1 to about 95% by weight of colorant of the total phase composition; optionally about 0.5 to about 50 weight %; optionally about 1 to about 25 weight%, and in certain aspects, optionally about 3 to about 15 weight %.

[0105] Moreover, the surface properties of each phase of the multiphasic particles can be tailored in a manner that provides control over the overall properties of the multiphasic particles. By varying the concentrations of colorants in the phases of the multiphasic particles and by including colorants for each of the primary colors, multiphasic particles of virtually any color can be obtained. Moreover, the multiphasic particles in accordance with the present teachings produce additional optical effects such as sheen, angular color variations, and translucence, if desired.

[0106] Multiphasic particles can be made of a wide variety of materials, including inorganic and organic materials. In various embodiments, at least one phase of the multiphasic colorant particles comprises at least one polymer, copolymer, or polymer precursor (e.g., monomer(s)), referred to herein generally as a “polymer.” The present disclosure employs a multiphasic particle comprising a first phase and at least one additional phase distinct from the first phase, where at least one of the first phase and the additional phase comprises a polymer or polymer precursor.Attorney Docket No. 2115-008421-WO-POA

[0107] The multiphasic particles can be made by a process involving electrified jetting used to create such anisotropic multiphasic particles. In suitable electrified jetting techniques, liquid jets having a nanometer- or micro-sized diameter are shaped using electro-hydrodynamic forces. When a pendant droplet of conductive liquid is exposed to an electric potential, for example, of a few kilovolts, the force balance between electric field and surface tension causes the meniscus of the pendent droplet to develop a conical shape, the so-called “Taylor cone.” Above a critical point, a highly charged liquid jet is ejected from the apex of the cone, thus forming a particle, such as a particle or fiber. Such electrical jetting techniques can be used in accordance with the present teachings to fabricate anisotropic microparticles or nanoparticles that can be useful for color or optical applications, where the special properties of the resulting colorant particles (amphiphilic, controlled pigment shapes, nano-scale design) lead to their usefulness in optical and electronic displays, for example. As noted above, in certain variations, multiphasic fibers are formed and then cut into microcylinders that transform into spherical microparticles.

[0108] Thus, methods of forming the multiphasic particles comprising colorants and materials capable of magnetization via electrified jetting include using liquid jets having a micrometer or nanometer- sized diameter exposed to electro-hydrodynamic forces. In certain aspects, the method of making multiphasic particles comprises combining at least a portion of two or more liquid streams (e.g., liquid jets) together such that the two or more liquid streams contact over spatial dimensions sufficient to form a composite liquid stream having a multiphasic conejet of micrometer or nanometer sized dimensions. In some variations, the liquid streams are electrically conductive. The composite liquid stream, and in particular the cone-jet, is exposed to a force field sufficient to solidify the composite liquid stream (z.e., the cone-jet) into a successive plurality of particles or fibers having multiple phases formed from materials originating in the respective first and second streams. In some variations, the present methods provide the ability to form the composite liquid stream fragments into droplets that lead to forming select shapes of particles.

[0109] Methods of forming core and shell structures include the side-by-side type of electrohydrodynamic (EHD) co-jetting technology methods described in U.S. Patent No. 7,767,017 to Lahann et al. and in PCT Publication No. WO 06 / 137936 to Lahann et al. the relevant portions of which are incorporated herein by reference, where the surface tension of respective two fluids being jetted, as well as the electric field application can be selected to promote formation of particles or fibers. In various aspects, the electric jetting methods can provide control over the morphology and design of the magnetoactive colorant particles as opposed to other methods of forming particles (such as sonication during liquid jetting and the like). For example,Attorney Docket No. 2115-008421-WO-POA the liquid jetting in the presence of an electric field of according to certain aspects of the present disclosure permits the use of immiscible materials as the first and second phases, as well as miscible materials. The broad use of such materials is possible due to the rapidity of formation of particles and shapes when an electric field is applied. For many conventional methods of formation, the respective phases require immiscibility between the phases; however, the electric jetting methods here do not require such immiscibility, thus resulting in a significant advantage and providing a wider range of material selection. Further, the methods of forming the multiphasic particles by use of side-by-side electric jetting further provide a high degree of control over the ability to create a wide variety of shapes, including fibers and the like.

[0110] In this regard, the multiphasic magnetoactive particles prepared by electrohydrodynamic jetting techniques described above may have a wide range of chemical, physical, and / or optical properties. Such multiphasic colorant particles can be designed to have pre-selected types and concentrations of materials capable of magnetization, particles receptive to other external force fields, colorants, or other active ingredients. Any number of suitable colorants can be used. Moreover, the surface properties of each exposed phase of the multiphasic colorant particles can be tailored, as desired, to change the overall properties of the particles.

[0111] In certain aspects, multiple phases of the multiphasic particles each comprise one or more polymers. In various aspects, the particles are formed by jetting liquid streams comprising a material optionally selected from liquid solutions, curable polymer precursors or monomers, polymer solutions, and polymer melts. Thus, each respective phase of the final particle product is formed from a material originating in the respective liquid streams. Specifically, each phase optionally contains polymers or polymer precursors (which upon curing form polymers), such as biodegradable or non-biodegradable polymers, biocompatible polymers, or natural polymers can be used. The particles can be further treated, for example by subsequent cross-linking induced by heat or actinic radiation (e.g., photochemically induced). Moreover, the cross-linking may also immobilize active materials, such as colorants, in the final product.

[0112] Thus, in certain aspects, the polymers can also be modified by chemical or physical methods after formation via electrified jetting, such as by cross-linking, heat treatment, photochemical treatment, and / or changes in the chemical or physical environment. The polymer modification can optionally occur in a select portion or region of one or more of the multiple phases, or such polymer modification can occur to different degrees, potentially resulting in different materials or materials responses, as appreciated by one of skill in the art.

[0113] In certain aspects, the first phase of the multiphasic particle comprises a first polymer and the second phase also comprises the first polymer. Specifically, various polymers,Attorney Docket No. 2115-008421-WO-POA including biodegradable or non-biodegradable polymers, biocompatible polymers, or natural polymers can be used. In other aspects, the first phase of the multiphasic particle comprises a first polymer and the second phase comprises a second polymer that is distinct from the first polymer. Thus, in certain aspects, different polymers can be used in at least two phases of the multiphasic particle composition.

[0114] Suitable non-limiting polymers for use in the multiphasic particles include poly(lactide-co-glycolide) polymer (PLGA), sodium polystyrene sulfonate (PSS), polyethers, such as a polyethylene oxide (PEO), polyoxyethylene glycol or polyethylene glycol (PEG), polyethylene imine (PEI), a biodegradable polymer such as a polylactic acid, polycaprolactone, polyglycolic acid, polyvinylpyrrolidone, and copolymers, derivatives, and mixtures thereof.

[0115] Water-soluble and / or hydrophilic polymers, which are cosmetically and pharmaceutically acceptable, include cellulose ether polymers, including those selected from the group consisting of hydroxyl alkyl cellulose, including hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), methyl cellulose (MC), carboxymethyl cellulose (CMC), and mixtures thereof. Other polymers among those useful herein include polyvinylpyrrolidone, vinyl acetate, polyvinylpyrrolidone-vinyl acetate copolymers, polyvinyl alcohol (PVA), acrylates and poly aery lie acid (PAA), including poly acrylate polymer, vinylcaprolactam / sodium acrylate polymers, methacrylates, poly(acryl amide-co-acrylic acid) (PAAm-co-AA), vinyl acetate and crotonic acid copolymers, polyacrylamide, polyethylene phosphonate, polybutene phosphonate, polystyrene, polyvinylphosphonates, polyalkylenes, and carboxy vinyl polymer. The multiphasic particle compositions may comprise derivatives, copolymers, and further combinations of such polymers, as well.

[0116] Other polymers or water-soluble fillers among those useful herein include, without limitation, sodium alginate, carrageenan, xanthan gum, gum acacia, Arabic gum, guar gum, pullulan, agar, chitin, chitosan, pectin, karaya gum, locust bean gum, various polysaccharides; starches such as maltodextrin, amylose, corn starch, potato starch, rice starch, tapioca starch, pea starch, sweet potato starch, barley starch, wheat starch, modified starch (e.g., hydroxypropylated high amylose starch), dextrin, levan, elsinan and gluten; and proteins such as collagen, whey protein isolate, casein, milk protein, soy protein, keratin, and gelatin.

[0117] Further, non-limiting examples of water insoluble or hydrophobic polymers include cellulose acetate, cellulose nitrate, ethylene-vinyl acetate copolymers, vinyl acetate homopolymer, ethyl cellulose, butyl cellulose, isopropyl cellulose, shellac, hydrophobic silicone polymer (e.g., dimethylsilicone), polymethyl methacrylate (PMMA), cellulose acetate phthalate and natural or synthetic rubber; siloxanes, such as polydimethylsiloxane (PMDS), polymersAttorney Docket No. 2115-008421-WO-POA insoluble in organic solvents, such as cellulose, polyethylene, polypropylene, polyesters, polyurethane and nylon, including copolymers, derivatives, and combinations thereof. The polymers may be crosslinked after formation by application of heat, actinic radiation or other methods of curing and treating polymers known to those of skill in the art.

[0118] Other polymers include those known in the art for use in paint compositions, ink compositions (including inkjet compositions), electronic ink compositions, and the like, including curable monomers or polymer precursors.

[0119] In various aspects of the present disclosure, the polymers (or polymer precursors) are present in a liquid phase prior to electrified jetting or spraying at about 0.1 to about 100% by weight (on a wet basis); optionally about 1 to about 90 weight %; optionally about 3 to about 75 weight % of the jetting stream. While the relative concentrations of polymers in a phase can vary greatly depending on the polymer, application, and process parameters used for forming the particle, in certain aspects, the polymer is optionally present at greater than or equal to about 2% to than or equal to about 50% by weight, optionally from greater than or equal to about 3% to less than or equal to about 15% by weight of the respective phase.

[0120] The structural components and the colorants typically form a single phase (exclusive of solvents, vehicles, and / or carriers) after the jetting process. The components are selected such that in certain aspects the components are thermodynamically compatible or alternately are thermodynamically incompatible with one another, depending on the desired properties of the multiphasic particles being formed. In the jetting process accompanying solvent evaporation and size reduction, even incompatible components can form a single phase by kinetic entrapment.

[0121] In yet another embodiment of the disclosure, multiphasic particles with selective chemical modification are provided. The particles are formed from one or more liquid streams that include one or more reactive components that react with a structural component (z.e., a polymer) thereby rendering a resulting surface of the multiphasic particles chemically modified as compared to the surface when the one or more reactive components are absent. For example, during the formation of multiphasic particles, reactive functional groups are optionally incorporated by adding appropriate components in each respective jetting solution. After jetting, the surface of the particle will have different functional groups at each respective phase surface corresponding to the materials present in each respective jetting solution. In some variations, the different phases are detected by optical or electronic sensors, or by fluorescent or electron microscopy, for example.Attorney Docket No. 2115-008421-WO-POA

[0122] In one aspect, the first phase of the multiphasic particle comprises a first polymer and the second phase comprises the first polymer, as well. In a further aspect, the first phase of the multiphasic particle comprises a first polymer and the second phase comprises a second polymer that is distinct from the first polymer. Thus, in certain aspects different polymers can be used in at least two phases of the multiphasic particle composition. In certain respects, different polymers used in the different phases of the multiphasic particles permit otherwise incompatible ingredients, such as colorants or other ingredients, to be stored simultaneously under stable conditions in near proximity to one another. In addition to colorants, respective phases may contain one or more materials capable of magnetization and optional additional ingredients, which may otherwise be incompatible with other active ingredients.

[0123] In various aspects, at least one of the phases comprises at least one material capable of magnetization and that is receptive to an external energy source (for example, a force field that is controllable, such as a magnetic field). The magnetizable material may refer to a material that inherently exhibits magnetic properties or that may be induced to exhibit magnetic properties. In certain aspects, the material capable of magnetization is selected from the group consisting of: iron (III) oxide (Fe2<D3) (e.g., yT^Ch), iron (II, III) oxide (FC3O4) (e.g., magnetite and FC3O4 nanocrystals), neodymium-iron-boron (NdFeB), manganese ferrite (MnFe2O4), cobalt ferrite (CoFe2O4), nickel iron oxide (NiFe2O4), nickel-iron alloys, chromium dioxide (CrC ), iron platinum (FePt), barium ferrite (BaFe or BaFenOw), and combinations, variations, and equivalents thereof.

[0124] In certain aspects, the magnetizable material is ferromagnetic or superparamagnetic. The multiphasic magnetoactive particles may comprise two or more distinct types of magnetizable materials and thus may be referred to as “hybrid” particles herein. In certain variations, the magnetizable material comprises a first material capable of magnetization that is ferromagnetic and a second material capable of magnetization that is superparamagnetic. The first and second materials capable of magnetization may be included in the same phase in certain variations, as will be described further below. In one aspect, the first material comprises neodymium-iron-boron (NdFeB) particles which are a ferromagnetic material. In another aspect, the second material comprises a superparamagnetic iron oxide nanoparticle (SPION).

[0125] An amount of magnetizable / magnetic materials included in one or more phases of the multiphasic particles will depend on the selection of the magnet, size of the optical device and optic feature, and the like. A concentration of magnetizable / magnetic materials, or magnetic payload, can be distributed anisotropically in different compartments or phases of a particle. In certain aspects, the material capable of magnetization / magnetic material may also beAttorney Docket No. 2115-008421-WO-POA the colorant for a given phase. In certain aspects, the particle capable of magnetization is present in the respective phase at optionally less than or equal to about 95 weight %, optionally less than or equal to about 85 weight %, optionally less than or equal to about 75 weight %, optionally less than or equal to about 65 weight %, optionally less than or equal to about 55 weight %, optionally less than or equal to about 50 weight %, less than or equal to about 45 weight %, optionally less than or equal to about 40 weight %, optionally less than or equal to about 35 weight %, optionally less than or equal to about 30 weight %, optionally less than or equal to about 25 weight %, optionally less than or equal to about 20 weight %, optionally less than or equal to about 15 weight %, optionally less than or equal to about 10 weight %, optionally less than or equal to about 5 weight %, optionally less than or equal to about 3 weight %, optionally less than or equal to about 1 weight %, and in certain aspects less than or equal to about 0.5 weight%. In certain aspects, each respective phase in the particle comprises about 0.1 to about 95% by weight of material capable of magnetization of the total phase composition, optionally about 0.5 to about 75 weight %, and in certain aspects, optionally about 1 to about 50 weight %.

[0126] In certain aspects, at least one of the phases of the particle optionally further contains an additional additive or component, for example inorganic microcrystals, inorganic nanocrystals, quantum dots, cross-linkers, and the like. In other aspects, multiple phases comprise may contain the same polymer, but differ in the additives present in each respective phase.

[0127] One of the phases may contain a redox-active material, a conducting material, a charged material, or a material with chemical groups that can react with the surrounding environment, medium, or substrate after the particles are produced. Further, in certain aspects, the particle may contain materials that enable the generation of an electrical potential in response to application of energy or radiation, such as a light pulse, for example, or an electrical potential comparable to a typical cell potential. In other aspects, the particle optionally has a component or has one or more exposed phase surfaces that promotes self-assembly of the particle on a substrate by enabling the relative orientation of the particles on a surface or substrate to build a selfassembled architecture.

[0128] The present disclosure also contemplates methods of forming swarming patterns in magnetoactive multiphasic (e.g., Janus biphasic) particles. The methods may comprise applying a magnetic force field to at least a portion of a plurality of multiphasic magnetoactive particles defining a magnetoactive material to exhibit a swarming pattern. The swarming pattern may be reconfigurable and thus capable of changing dynamically. Each particle defines at least two optically distinct phases. Each may comprise a first phase comprising a first colorant and at least one additional phase distinct from the first phase, so that each particle defines the optically distinctAttorney Docket No. 2115-008421-WO-POA phases. Further, at least one of the first phase or the at least one additional phase comprises a material capable of magnetization, so that when the magnetic force field is applied, the plurality of multiphasic magnetoactive particles defining the swarming pattern change position. In certain aspects, only a first portion of the plurality of magnetoactive multiphasic particles define the swarming pattern when the magnetic force field is applied, while a second portion of the plurality of magnetoactive multiphasic particles do not change position or other discernable characteristics so as to provide a visible contrast with the first portion of the plurality of multiphasic magnetoactive particles defining the swarming pattern.

[0129] Magnetoactive multiphasic (Janus biphasic) particles (MAJPs) formed in accordance with certain aspects of the present disclosure can be used as metamaterials. Metamaterials are emerging as an unconventional platform to perform computing abstractions in physical systems by processing environmental stimuli into information. While computation functions have been demonstrated in mechanical systems, they rely on compliant mechanisms to achieve predefined states, which impose inherent design restrictions that limit their miniaturization, deployment, reconfigurability, and functionality. Here, a metamaterial system based on responsive magnetoactive Janus particle (MAJP) swarms with multiple programmable functions is contemplated. Magnetoactive multiphasic (Janus biphasic) particles (MAJPs) were designed with tunable structure and properties in mind, e.g., encoded swarming behavior and fully reversible switching mechanisms, to enable programmable dynamic display, non-volatile and semi-volatile memory, Boolean logic, and information encryption functions in soft, wearable devices. Magnetoactive multiphasic (Janus biphasic) particles (MAJPs) and their unique swarming behavior open new functions for the design of multifunctional and reconfigurable display devices, and constitute a promising building block to develop the next generation of soft physical computing devices, with growing applications in security, defense, anti-counterfeiting, camouflage, soft robotics, and human-robot interaction.

[0130] Examples

[0131] Magnetoactive multiphasic (Janus) particle (MAJP) fabrication can be formed as follows, magnetoactive multiphasic particles (MAJPs) were fabricated by first producing biphasic / Janus microfibers from polylactic glycolic acid (PLGA) (ester termination, MW 50-75 KDa, Sigma Aldrich) solution through an electrohydrodynamic (EHD) co-jetting process. To prepare the solution, magnetic particles (<50 nm particle diameter SPIONs and 5 pm particle diameter NdFeB microparticles) and 200 nm TiCh particles were dispersed in a mixture of chloroform and N,N-dimethylformamide (DMF) (95:5 v / v) using a Qsonica q700 ultrasonicator. PLGA was added to the dispersion at a 37.5% w / v concentration, maintaining a PLGA:particleAttorney Docket No. 2115-008421-WO-POA ratio at 5.7% w / w. The PLGA / particle precursors were loaded in two separate 1 mL syringes with 25 G co-aligned needles. The precursor dispersions were then pulled from the needles by an 8 kV driving voltage (Gamma High Voltage Research) applied between the needle tip and the ground (15 cm distance) assisted by a syringe pump at a constant flow rate of 0.05 mL / h. Co-jetted Janus microfibers were dried and stored in a vacuum desiccator for 2 days for solvent evaporation. The dried fibers were then embedded in optimal cutting temperature (OCT) cutting gel and microsectioned using a microtome (Epredia NX50) at 350 pm. The sectioned microcylinders were suspended in OCT water solution (OCT served as surfactant and viscosity modifier), and were shape-transformed into spherical particles by surface energy minimization using ultrasonication (Qsonica q700 with 1 / 8” microtip probe for 15 minutes). The resulting magnetoactive multiphasic particles (MAJPs) were washed with DI water to remove the OCT surfactant, and stored in DI water for later use.

[0132] Scanning electron microscopy (SEM).

[0133] Magnetoactive multiphasic (Janus biphasic) particles (MAJPs) were coated with a gold film (thickness of 10-20 nm) in an SPI-Module Sputter Coater and imaged on the Thermo Fisher Nova 200 Nanolab SEM. The energy dispersive spectroscopy (EDS) function was used to image titanium and iron elements.

[0134] Magnetic characterization. The magnetic hysteresis loops of MAJPs were measured at room temperature in a Lake Shore 7400 vibrating sample magnetometer. The particles were dried at room temperature in a vacuum desiccator and mounted on a sample holder. The measurements were made using a scanning field within the range of ±1.9 T, and were background subtracted and normalized by the sample weight. The VSM was later utilized to test the magnetic stability of different MAJP types. After exposure to a high magnetic field (2 T), the magnetizations of the particles were measured at zero fields, and comparable fields within the actuation field range (50-100 mT).

[0135] Magnetoactive multiphasic particle (MAJP) swarm cell fabrication occurs as follows. PET sheets with 0.15 mm thickness were laser-cut into the desired shapes (e.g., 3 x 3 cm rectangles), and adhesive gaskets from mounting tapes were cut accordingly using a puncture tool. After attaching one side of the mounting tape gasket to one PET substrate, the MAJP suspension was transferred to the well and then sealed with another PET film on top (FIG. 8). Trapped air pockets were removed with two 18G 3 inch hypodermic needles (with one needle injecting water and the other suctioning air). Due to the elastomeric and self-adhesive properties of the mounting tape, the needle holes were sealed without leaking.Attorney Docket No. 2115-008421-WO-POA

[0136] Magnetic actuation using homogeneous fields. Magnetoactive multiphasic particle (MAJP) swarms and devices were exposed to homogeneous magnetic fields (global direction) generated by either an electromagnet (Bunting BDE-4032-12, with a DC power supply Tekpower TP3005P) spanning ±84 mT or permanent NdFeB magnets for larger fields. Actuation fields < 20 mT were used to rotate the MAJPs by generating magnetic torques on the particles, and > 50 mT were used to rewrite the polarity of SPM MAJPs. Alternating combinations of low (< 20 mT) and high (> 50 mT) magnetic fields were used to actuate SPM, FM, and hybrid MAJPs selectively in our swarm devices. A Nikon camera (D3500) was used to record the swarm states and transitions, and the images were later analyzed using Image (version: 1.53e) with the color threshold function to quantify brown vs orange pixels.

[0137] Magnetic actuation using structured fields. Structured magnetic fields (heterogeneous fields with varying intensity and direction over the actuation plane) were generated with arrays of small NdFeB permanent magnets (0: 2 mm, height: 1 mm, FINDMAG). Magnet array holders with 1 mm thickness with simple cubic or hexagonal close-packed 2 mm diameter holes and 1 mm spacings were 3D-printed (SL1S, Prusa research), and the disk magnets were then assembled in the holders with predefined directions and patterns, resulting in structured magnetic fields. The patterns of the structured fields were visualized using a magnetic flux display film (Learay Magnets).

[0138] Design of semi- volatile and non-volatile memory in MAJP swarms. MAJP swarms exhibited static semi-volatile patterns when a structured low-intensity field was applied (magnet array placed at > 1 mm from swarm cell). Dynamic semi-volatile patterns were similarly exhibited under a mobile magnet array under the swarm cell. These patterns disappear after removal of the field and upon applying a new field. Non-volatile memory was achieved by selectively rewriting SPM MAJP swarms under high-intensity fields (> 50 mT, achieved by positioning the magnet arrays at < 1 mm under the swarm cell). The pattern was then displayed upon exposure to a new homogeneous field, remaining stable after the field is off and after mechanical agitation. These concepts were demonstrated on single swarm devices and on a wearable device mounted on a nitrile glove.

[0139] Design of Boolean functions in magnetoactive multiphasic particle (MAJP) swarms. “AND” and “OR” logic gates were fabricated by combining responsive (SPM and hybrid) MAJPs and passive (solid color) particles into a single swarm. The two types of MAJPs were actuated independently, thus providing the two inputs of the gates, while the passive particles were added to tune the color baseline and the output response. To determine the transition threshold between the ON and OFF states, a randomized color perception test was performed with variationsAttorney Docket No. 2115-008421-WO-POA in magnetoactive multiphasic particle (MAJP) swarm compositions with n = 46 participants (HUM00236320, exempt from IRB review), resulting in a threshold of 45%. The magnetoactive multiphasic particle (MAJP) swarm composition were then tuned accordingly: the AND swarm gate was composed of 40% SPM MAJP, 40% hybrid MAJP, and 20% TiCh passive particles, and the OR swarm gate was composed of 40% SPM MAJP, 40% hybrid MAJP, and 20% SPION passive particles.

[0140] Design of encryption mechanisms in magnetoactive multiphasic particle (MAJP) swarms. The encryption process requires an encryption key and a decryption key, both generated with structured magnetic fields from arrays of permanent magnets with pre-programmed polarities. The encryption key is first applied at high-intensity, thus rewriting the magnetization of the swarm and encoding the desired pattern as semi-volatile memory. Under a homogeneous reading field (public message), the encryption pattern is displayed. The complementary decryption key field is applied at low intensity, performing a XOR function with the encryption key and displaying the private message only under the combination of the two keys.

[0141] The magnetoactive components that comprise magnetoactive multiphasic particles capable of reversible and controllable swarming behavior are particularly suitable for use as bits in a reconfigurable memory system, as pixels in optic display applications or to create an optic feature, or for generating imprinted encryption insignia for encryption displays. The swarm patterns can be created by applying magnetic fields controlling the relative state (e.g., orientation) of at least a portion of the plurality of magnetoactive multiphasic particles to a substrate, as well as to other particles. The change in particle state is due to the influence of the controllable, external magnetic force field. Thus, in accordance with the present teachings, a multiphasic magnetoactive particle constituting at least a portion of the plurality of particles in the display component has at least one phase which comprises a material or component that is capable of magnetization and thus receptive to a controllable external force field, such as a magnetic field. Thus, in response to the switching or other alteration of the transmitted magnetic field, re-orientation of at least a portion of the magnetoactive multiphasic particles is observed, which results in a change in a state of the particle swarm to define a swarm pattern (e.g., changing optical properties to define a display pattern).

[0142] Thus, in various aspects, the present disclosure pertains to a multifunctional swarm metamaterial system based on magnetoactive multiphasic (e.g., Janus) particles (MAJPs) providing collective or swarming actuation for adaptive coloration and pattern displays. In certain aspects, magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure can dynamically switch between predefined color states. MAJPsAttorney Docket No. 2115-008421-WO-POA were designed and fabricated by electrohydrodynamic (EHD) co-jetting with engineered functional compartments for high contrast and addressable magnetic actuation. The programmable properties of MAJP swarms can concurrently enable fast response, remote actuation, and memory functions in electronics-free configurations, which facilitate integration in soft and flexible devices like wearable devices. These modular configurations impart programmable magnetoactive behaviors and switching mechanisms in multifunctional active swarms, which enable advanced dynamic display, computation, non-volatile and semi-volatile memory, and encryption functions compatible with soft, wearable devices.

[0143] Design and fabrication of a particle-based display system comprising magnetoactive multiphasic particles (Janus particles (MAJPs)) according to certain aspects of the present disclosure are described herein. In various aspects, the display system comprises magnetoactive multiphasic particles with at least two functionally distinct compartments, each comprised of a precisely tailored composition with distinct magnetic and optical properties. These functional particles were fabricated by electrohydrodynamic (EHD) co-jetting, which produced polylactic glycolic acid (PLGA) bicompartmental fibers that were later transformed into magnetoactive multiphasic (specifically biphasic) particles (MAJPs). Briefly, precursor solutions were prepared by dissolving and dispersing PLGA and particulate dopants in a mixture of solvents, which were then electrojetted using co-aligned needles under high voltage (FIG. 1A and FIG. 6). During the EHD co-jetting process, as described above, charged liquid droplets are pulled from the needles by a high electric field, forming thin, long fibers that are rapidly solidified due to fast solvent evaporation. The resulting bicompartmental fibers had a constant diameter of 300 micrometers and a clear boundary between the magnetic (brown) and the pigment (white) compartments (FIGS. 7A-7B). The fibers were microsectioned into short cylinders (aspect ratio approximately 1) using a conventional microtome and processed via ultrasonication in water. Under these conditions, the microcylinders underwent a shape-transformation process into spherical particles, a process that is driven by surface energy minimization (FIG. IB). To fabricate a magnetoactive component in the form of a swarm cell for particle-based display devices, a magnetoactive multiphasic particle (MAJP) suspension was encapsulated between two poly(ethylene terephthalate) (PET) substrates and clear adhesive spacers, resulting in a flexible, transparent, and robust device casing (FIG. 1C, FIG. 8). When exposed to a magnetic field, magnetoactive multiphasic particles (MAJPs) exhibit a swarming behavior synchronously rotating with the external magnetic field direction (FIG. ID). The particle swarm exhibits emergent properties of a magnetomechanical metamaterial where magnetic stimuli are coupled to a mechanical response. Under an external magnetic field (magnetic stimulus), the particlesAttorney Docket No. 2115-008421-WO-POA experience a magnetic torque that depends on the actuation field (controllable), particle magnetization (tunable by particle design and fabrication), and the angle between them. As a result, the torque induces rotational motion (mechanical response) to align the particles with the field. By switching the magnetic field direction (normal to the display), two high-contrast color states can be observed, demonstrating fast and reversible two-state transitions in the swarm (FIG. IE). The size of the magnetoactive multiphasic particle (MAJP) was optimized for high-contrast switching between the two states (FIG. 9). While each individual particle has two possible color states (one phase / compartment facing up or the other) in response to magnetic fields, the collective behavior of MAJPs exhibits visual emergent complexity in the form of swarming patterns with encoded information.

[0144] In the following sections, three magnetoactive multiphasic particle (MAJP) types with distinct magnetic properties and switching behaviors under magnetic fields, and spatiotemporal structured fields are designed to enable complex display, Boolean logic, memory, and encryption functions in programmable swarm metamaterials.

[0145] Design of magnetoactive Janus particles (MAJPs) and swarming behavior. Here, magnetoactive multiphasic particles (MAJPs) are designed with two opposed compartments: a brown-colored compartment with predefined combinations of 5 micrometer (pm) NdFeB ferromagnetic microparticles and 50 nm superparamagnetic iron oxide nanoparticles (SPIONs), and a white-colored compartment with titanium dioxide (TiO2) pigment for contrast (FIG. 2A). Scanning electron microscopy (SEM) and energy dispersion X-ray spectroscopy (EDS) confirmed a biphasic distribution of Ti and Fe, showing a clear boundary between phases / compartments at the equator of the particle. NdFeB and SPION particles dispersed in the magnetic compartment are used to induce forces and torques on the magnetoactive multiphasic particles (MAJPs); however, they each provide a distinct response to external magnetic fields (FIG. 2B). Ferromagnetic magnetoactive multiphasic particles (MAJPs) (FM, composed of NdFeB) have high saturation magnetization and high remanence (z.e., high magnetization is conserved when the field is removed). Superparamagnetic magnetoactive multiphasic particles (MAJPs) (SPM, composed of SPIONs) have lower saturation magnetization and near- zero remanence (z.e., magnetization is not conserved when the field is removed). Hybrid MAJPs (composed of both NdFeB and SPIONs in the same compartment) have combined properties, with high saturation magnetization but low-moderate remanence. These properties translate to distinct polarization behavior for each magnetoactive multiphasic particle (MAJP) type (FIG. 2C). After an initial premagnetization step, each MAJP type retained different levels of magnetization, and were then exposed to oscillating fields to characterize their switching behavior. While FM MAJPs preservedAttorney Docket No. 2115-008421-WO-POA their magnetization, SPM MAJPs changed magnetization direction according to the applied field, oscillating around zero. Hybrid MAJPs exhibited a combined behavior, oscillating around its remanence but maintaining constant direction. Without an initial pre-magnetization step, all MAJP types oscillated around zero magnetization, and FM dopants contributed with weak magnetic moments compared to SPM (FIG. 10).

[0146] As a result of their distinct magnetic properties, each magnetoactive multiphasic particle (MAJP) type exhibited characteristic collective switching behavior in particle swarms under varying magnetic fields (FIG. 2D). Ferromagnetic (FM) magnetoactive multiphasic particles (MAJPs) did not align synchronously and did not exhibit homogeneous collective color states in the swarm in either configuration (at negative and positive fields) due to their initial low magnetization. On the other hand, superparamagnetic (SPM) magnetoactive multiphasic particles (MAJPs) align synchronously under small fields, exhibiting homogeneous swarm color states with high contrast. However, their magnetization is reversed at larger fields (>20 mT) due to their low remanence, thus switching their swarm state under the same field direction. Hybrid magnetoactive multiphasic particles (MAJPs) (combining SPM and FM in the same compartment) can be aligned synchronously under small fields and then permanently magnetized to fix their polarization (FIGS. 11A-11B). As a result, hybrid magnetoactive multiphasic particles (MAJPs) exhibit homogeneous synchronous swarm alignment, high color contrast between swarm states, and high stability (swarm states are stable under the same field direction, regardless of magnitude). The composition of the hybrid magnetic compartment (NdFeB:SPION ratio) was optimized for stability and contrast (FIGS. 12A-12C). Full-color hysteresis maps in a magnetic field sweep cycle of all three magnetoactive multiphasic particle (MAJP) swarm systems (FIGS. 13A-13C) confirmed the reversibility of the color-state transitions with their distinctive switching behaviors.

[0147] Magnetoactive multiphasic particles (MAJPs) swarms with Boolean logic functions are created as follows. Leveraging their characteristic switching mechanisms, magnetoactive multiphasic particle (MAJP) swarms are designed with different responsive behaviors under the same input field. This approach enables programming multiple states in the swarms beyond the single binary states of individual particles. For example, two states in a swarm as ON (1) and OFF (0) determined by the magnetoactive multiphasic particles (MAJPs) orientation can be defined and collective displayed color (brown compartment up and white compartment up respectively). A swarm with a single type of magnetoactive multiphasic particle (MAJP) can act as a binary 1-bit system that displays a collective color state as a function of magnetic field. By combining different types of magnetoactive multiphasic particle (MAJP) swarms, higher complexity responses can be programmed in multi-bit display systems. ToAttorney Docket No. 2115-008421-WO-POA demonstrate this concept, a 2-bit system is designed combining SPM (left) and hybrid (right) swarms (FIG. 3A) under the same magnetic field (both swarms subjected to the same global input field conditions at all times). Initially, both swarms are aligned together with the field (state 0,0), and can reversibly alternate their state by switching the field direction (state 1,1). However, the magnetization of SPM swarms can be rewritten at higher fields, while preserving the magnetization of hybrid swarms. This reversible transition enables access to the intermediate 0,1 and 1,0 states where SPM and hybrid swarms align synchronously but oppositely under the same homogeneous field (FIG. 14). Therefore, by controlling the global magnetic field direction and intensity, four interchangeable states can be accessed in this 2-bit, two-swarm MAJP system (which could be readily extended to higher number of bits for higher complexity) . Hybrid particles can also be reprogrammed and their polarization reversed by applying an initial high-intensity pulse to give access to further programmable states and responses under the same field (FIG. 15).

[0148] In addition to programming swarms as individual bits, different types of magnetoactive multiphasic particles (MAJPs) can be combined in a heterogeneous swarm configuration. This approach enables the design of magnetoactive multiphasic particle (MAJP) complex swarms with programmable output states as a function of a single actuation stimulus, akin to other metamaterial structures developed for mechanical computing. To demonstrate this concept, responsive (SPM and hybrid) magnetoactive multiphasic particles (MAJPs) and passive (solid TiO2 and SPION) particles are integrated into complex swarms to provide a broad spectrum of programmable functions (FIG. 3B). Swarm logic gates with “AND” and “OR” Boolean functions are designed, with a programmable collective output state as a function of swarm composition and MAJP magnetoactive response (FIG. 3C). These magnetoactive multiphasic particle (MAJP) logic swarms exhibit the programmed behavior corresponding to their respective Boolean function truth tables. The output states of the complex logic swarms based on magnetoactive multiphasic particle (MAJP) calibration are discretized (FIG. 16) and human color perception tests (FIGS. 17A-17B), resulting in a consensus on / off switching threshold at 45%. This concept of functional responsive swarms can be easily miniaturized and integrated into multicell devices, and further expanded with dynamic and structured actuation fields for more advanced complex functions.

[0149] Display and memory functions of magnetoactive multiphasic particle (MAJP) swarms prepared according to certain aspects of the present disclosure are explored herein. MAJP swarms can display complex information by actuating selected particles only, exhibiting locally structured patterns rather than global on / off states. Actuation magnetic fields were spatially programmed by designing small-scale permanent magnet arrays arranged in specified orientationsAttorney Docket No. 2115-008421-WO-POA(FIG. 18), resulting in heterogeneously structured fields with programmed on and off regions. When applied to magnetoactive multiphasic particle (MAJP) swarms, the particles align heterogeneously to the programmed structured field and display complex patterns in the swarm (FIG. 4A). Because magnetic actuation does not require direct contact, the actuation arrays can be moved remotely, thus generating spatiotemporally heterogeneous fields and resulting in dynamic patterns with complex information (such as moving figures, rotating directions, sliding text, etc.) (FIGS. 4B, 19A-19C).

[0150] This selective switching actuation approach expands the display capabilities of magnetoactive multiphasic particle (MAJP) swarms beyond 1 -bit global behavior, both providing new design opportunities for emergent swarming patterns and enabling dynamic display functions. Furthermore, this information can be stored in the magnetization states of magnetoactive multiphasic particles (MAJPs) as a semi-volatile and non-volatile memory system. Conventional computer and mechanical memory terminology is adapted here to describe memory functions of magnetoactive multiphasic particles (MAJPs) according to certain aspects of the present disclosure: (i) volatile memory requires power input (or in this case, an actuation field) to maintain the stored information (displayed pattern), but the information is lost when the field is removed. On the other hand, (ii) non-volatile memory does not lose the information when the field is removed. In between of the two, (iii) semi-volatile memory has non-volatility but for a limited duration (the memory is degraded over time or disrupted by external agents). In semi- volatile memory mode (FIG. 4C), a low-intensity structured field is applied which rotates and aligns the particles in a specific pattern. The particle orientation and displayed pattern remain after the field is removed; however, the information can be erased when a new field is applied. In non-volatile memory mode (FIG. 4D), a high-intensity structured field is applied which rewrites the magnetization of particles in a specific pattern, encoding the information permanently. The displayed pattern is preserved after the field is removed and after new fields are applied. This nonvolatile memory mechanism is further demonstrated in magnetoactive multiphasic particle (MAJP) swarms integrated in a wearable soft display device mounted on a glove (FIG. 4E), where an “M” is encoded and displayed with an homogeneous field activation pulse. The pattern is not erased when the field is removed, but it can be erased with mechanical agitation (causing the particles to reorient randomly). However, since it has been encoded in the structured magnetization of the swarm, the pattern is recovered and displayed again under another homogeneous field pulse without loss of information. Therefore, magnetoactive multiphasic particle (MAJP) swarms and their integrated soft display devices offer highly-stable non-volatileAttorney Docket No. 2115-008421-WO-POA memory without energy input and under mechanical perturbations or deformation, which enables their operation and deployment in wearable technology for unstable working environments.

[0151] Reconfigurable encoding and encryption of complex information. Taking advantage of the memory properties of magnetoactive multiphasic particle (MAJP) swarms, an encryption mechanism is designed to display information only under specific and programmable conditions. This mechanism is based on the XOR operation of superimposed non-volatile and semi- volatile memory functions on a SPM-MAJP swarm (FIG. 5A). First, a pattern is encoded (e.g., imprinted) by applying a structured magnetic field (encoding key), locally rewriting the magnetization of the swarm according to the predefined key (non-volatile writing). Then, a second structured field (reading key B^) is applied, selectively actuating only those regions of the swarm where its encoded magnetization is misaligned (semi-volatile reading). As a result, a complex displayed pattern is observed due to the XOR operation of encoding and reading key fields ®ET in the swarm, generating a unique pattern that is not possible with either key field alone. This concept was adapted to the proposed encryption mechanism, where the structured encoding field has an encryption key function and the reading field has a decryption key function (FIGS. 5B, 20). For example, to communicate a target message of “o”, a MAJP swarm is encoded with an arbitrary encryption key field, displaying a public message of “x” when read with a homogeneous field without the proper key. Only when the unique complementary decryption key is applied the private message of “o” can be read. This swarm encryption system is versatile and scalable, and can be adapted to arbitrary key patterns to display different information under different conditions. For example, for a specific encrypted swarm displaying a public message of “x”, three different decryption keys were programmed to display private messages of“o”, respectively (FIG. 5C, FIG. 16), thus displaying different messages from the same original encrypted message using. Oppositely, multiple encryption / decryption key pairings can be designed for a single message so that only the right combination displays the target private message (FIGS. 5D, 22). To illustrate this, three encryption keys displaying a public message of , were designed, with their respective complementary decryption paired keys to display a target private message of “o”.

[0152] The magnetoactive multiphasic particle (MAJP) swarm systems provided in accordance with various device configurations according to the present disclosure have diverse programmable functions that arise from the rational design of a family of responsive multiphasic (e.g., bicompartmental Janus) particles. By carefully designing the magnetoactive multiphasic particle (MAJP) swarm configuration and its magnetoactive properties, the responsiveness of magnetoactive multiphasic particles (MAJPs) can be tailored to magnetic fields based on varyingAttorney Docket No. 2115-008421-WO-POA magnetization, remanence, and stability, resulting in distinct and programmable switching behaviors. The design of unusual colloidal materials and their programmable behaviors opens a broad design space for complex display functions beyond global on / off switching, which constitutes a major breakthrough in the fields of reflective displays, responsive metamaterials, and soft robotic matter. More specifically, the design of MAJPs with tunable responsiveness under magnetic fields enabled non-volatile and semi- volatile memory mechanisms for the display of complex and dynamic graphic information in functional swarms. While the resolution of the graphics is intrinsically limited by the particle size and the structural resolution of the applied fields, these are easily scalable (both up and down) in size to fit particular message- and application-specific requirements. Due to their modular design (bottom- up hierarchical design of individual particles, their swarm switching properties, and swarm composition and structure to program the global response), magnetoactive multiphasic particle (MAJP) display systems can also be scaled up to large swarms with wide working areas or miniaturized into smaller cells in multi-pixel metamaterial arrays, both providing a versatile platform for displaying more complex information. The integration of non-volatile and semi-volatile memory in heterogeneous particle swarms has enabled the design of logic gates and encryption functions for applications in mechanical computing and security. Unlike other graphic encryption mechanisms that typically rely on single-key (null-to-image transitions), the present magnetoactive multiphasic particle (MAJP) swarm system relies on a two-key XOR operator encryption mechanism, thus increasing the security and the specificity of the device. While most encryption systems relying on mechanical metamaterials are designed for a single specific message that cannot be modified once fabricated, the magnetoactive multiphasic particle (MAJP) swarm display system offers excellent versatility and reconfigurability as the keys can be immediately exchanged on demand for new messages. Furthermore, magnetoactive multiphasic particle (MAJP) swarms are easy to deploy and integrate in flexible devices as demonstrated, including wearables and other portable technology, for soft, flexible, durable, light-weight, electronics-free, and resilient (preserve function and encoded information under mechanical agitation and stress) performance. Further, magnetoactive multiphasic particles (MAJPs) are not limited to configurations with two equally sized hemispheres, and complex particles with more than two compartments and / or different compartment sizes could provide access to a broad range of swarming behaviors and states that can be tailored toward particular functions. Because of their programmable switching properties and unique functions in computation, memory, and encryption functions, magnetoactive multiphasic particle (MAJP) swarms are promising colloidal building blocks to develop the nextAttorney Docket No. 2115-008421-WO-POA generation of soft display devices, with growing applications in personal security, defense, anticounterfeiting, camouflage, soft robotics, and human-robot interaction.

[0153] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

Attorney Docket No. 2115-008421-WO-POACLAIMSWhat is claimed is:

1. A magnetoactive material comprising: a plurality of multiphasic magnetoactive particles configured to selectively exhibit a swarming pattern when a magnetic force field is applied, each particle comprising a first phase comprising a first colorant and at least one additional phase distinct from the first phase so that each multiphasic magnetoactive particle has optically distinct phases and at least one of the first phase or the at least one additional phase comprises a magnetizable material receptive to the magnetic force field.

2. The magnetoactive material of claim 1 , where the magnetizable material is selected from the group consisting of: iron (III) oxide (Fe2O3), iron (II, III) oxide (FC3O4), neodymium- iron-boron (NdFeB), manganese ferrite (MnFe2O4), cobalt ferrite (CoFe2O4), nickel iron oxide (NiFe2<34), nickel-iron alloys, chromium dioxide (CrCh), iron platinum (FePt), barium ferrite (BaFe or BaFenOw), and combinations thereof.

3. The magnetoactive material of claim 1, where the magnetizable material is ferromagnetic or superparamagnetic.

4. The magnetoactive material of claim 1 , where the magnetizable material comprises a first magnetizable material that is ferromagnetic and a second magnetizable material that is superparamagnetic .

5. The magnetoactive material of claim 4, wherein the first magnetizable material comprises neodymium-iron-boron (NdFeB).

6. The magnetoactive material of claim 4, wherein the second magnetizable material comprises a superparamagnetic iron oxide nanoparticle (SPION).

7. The magnetoactive material of claim 1, wherein the plurality of multiphasic magnetoactive particles has an average particle size of greater than or equal to about 300 micrometers to less than or equal to about 500 micrometers.

8. The magnetoactive material of claim 1, wherein the swarming pattern is reconfigurable.

9. A magnetoactive device comprising: a magnetoactive component comprising a plurality of multiphasic magnetoactive particles configured to selectively exhibit a swarming pattern when a magnetic force field is applied, each particle comprising a first phase comprising a first colorant and at least one additional phase distinct from the first phase so that each multiphasic magnetoactive particle hasAttorney Docket No. 2115-008421-WO-POA optically distinct phases and at least one of the first phase or the at least one additional phase comprises a magnetizable material receptive to the magnetic force field.

10. The magnetoactive device of claim 9, further comprising a magnetic component for selectively generating the magnetic force field directed towards the magnetoactive component, where the magnetic force field is configured to induce swarming behavior in at least a portion of the plurality of the magnetoactive multiphasic particles.

11. The magnetoactive device of claim 9, where the magnetizable material is selected from the group consisting of: iron (III) oxide (Fe2O3), iron (II, III) oxide (FC3O4), neodymium- iron-boron (NdFeB), manganese ferrite (MnFe2O4), cobalt ferrite (CoFe2O4), nickel iron oxide (NiFe2<D4), nickel-iron alloys, chromium dioxide (CrCh), iron platinum (FePt), barium ferrite (BaFe or BaFenOw), and combinations thereof.

12. The magnetoactive device of claim 9, where the magnetizable material is ferromagnetic or superparamagnetic.

13. The magnetoactive device of claim 9, where the magnetizable material comprises a first magnetizable material capable of magnetization that is ferromagnetic and a second magnetizable material capable of magnetization that is superparamagnetic.

14. The magnetoactive device of claim 13, wherein the first magnetizable material comprises neodymium-iron-boron (NdFeB).

15. The magnetoactive device of claim 13, wherein the second magnetizable material comprises a superparamagnetic iron oxide nanoparticle (SPION).

16. The magnetoactive device of claim 9, wherein the plurality of multiphasic magnetoactive particles has an average particle size of greater than or equal to about 300 micrometers to less than or equal to about 500 micrometers.

17. The magnetoactive device of claim 13, wherein the swarming pattern is reconfigurable.

18. The magnetoactive device of claim 13, wherein the magnetoactive component is a swarm cell having a chamber comprising a liquid and the plurality of multiphasic magnetoactive particles disposed therein.

19. The magnetoactive device of claim 13, wherein the magnetoactive device is a portable device or a wearable device.

20. The magnetoactive device of claim 13, wherein the magnetoactive component defines at least one bit of memory.Attorney Docket No. 2115-008421-WO-POA21. The magnetoactive device of claim 20, wherein the at least one bit of memory is selected from the group consisting of: non-volatile memory, semi-volatile memory, and volatile memory.

22. The magnetoactive device of claim 13, wherein the magnetoactive device forms part of an encryption system and the swarming pattern is encrypted.

23. The magnetoactive device of claim 13, wherein the magnetoactive component defines a portion of a display component and the magnetoactive device is a display device or an optical device.

24. The magnetoactive device of claim 13, wherein the swarming pattern has been encoded or imprinted by an initial magnetization process.

25. A method of forming a swarming pattern in a magnetoactive material, the method comprising: applying a magnetic force field to the magnetoactive material that comprises a plurality of multiphasic magnetoactive particles to exhibit a swarming pattern, wherein each particle comprises a first phase comprising a first colorant and at least one additional phase distinct from the first phase to define optically distinct phases, wherein at least one of the first phase or the at least one additional phase comprises a magnetizable material, so that at least a portion of the plurality of multiphasic magnetoactive particles change position to define the swarming pattern.

26. The method of claim 24, wherein only a first portion of the plurality of magnetoactive multiphasic particles define the swarming pattern during the applying of the magnetic force field, while a second portion of the plurality of magnetoactive multiphasic particles do not change position or exhibit other discernable characteristics during the applying of the magnetic force field to provide a visible contrast with the first portion of the plurality of multiphasic magnetoactive particles defining the swarming pattern.

27. The method of claim 25, wherein the swarming pattern is reconfigurable.

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